* Pro-Mubarak forces charge into the crowd on horses and camels * The police are nowhere to be seen and the army does little * Protesters hurl rocks and several people are wounded * Some pro-Mubarak demonstrators say they are forced to demonstrate

Cairo, Egypt (CNN) -- A dramatic and potentially deadly situation unfolded Wednesday at the epicenter of Cairo's demonstrations as pro- and anti-government forces clashed, and supporters of embattled President Hosni Mubarak thundered through the crowds on horses and camels in Tahrir Square.

At least one man was pulled off his horse and beaten.People hurled verbal insults, rocks and anything else they could find -- shards of metal, sticks, shoes -- at one another. They beat each other in what quickly turned into utter mayhem. But despite the extremely volatile altercations, the police were nowhere to be seen and the army did little.

Blood streamed down the faces of some protesters, who were carried away from the square into a nearby makeshift clinic. Others climbed atop army tanks, waving flags and chanting loudly.

The melee erupted after pro-Mubarak demonstrators broke through a barricade separating them earlier from anti-government protesters who have been amassing for nine days in the downtown plaza that has become the symbol of Egypt's uprising.

Contesting rallies were also taking place further north in the Mediterranean city of Alexandria.

Earlier in Cairo, the crowds were smaller and the mood different on the streets the day after Mubarak announced his intention not to seek re-election and the military urged protesters to return the nation to normalcy.

"Your message is received ... (your) demands became known," a Defense Ministry spokesman said on state-run television. "And we are here and awake to protect the country for you ... not by power but by the love to Egypt. It is time to go back to normal life."

Angry Egyptians, fed up with Mubarak's rule, have camped out in the Egyptian capital's central plaza for a week. The burgeoning demonstrations led to the "march of millions" on Tuesday.

On Wednesday, the voices defending the government were louder. They called the media "traitors" and "agents" and said the country cannot survive without Mubarak. It was unclear how many were out on the streets from their own volition. Three employees of the national petroleum company told CNN they were forced to demonstrate Wednesday.

In a televised address Tuesday night, Mubarak announced he will not seek office again in elections scheduled for September, but vowed to stay in the country and finish his term.

"My first responsibility now is to restore the stability and security of the homeland, to achieve a peaceful transition of power in an environment that will protect Egypt and Egyptians, and which will allow for the responsibility to be given to whoever the people elect in the forthcoming elections," Mubarak said in a televised address Tuesday night.

The concession, large and remarkable for a man who has held a tight grip on power for three decades, may have been too little and too late for many Egyptians.

"He is unfortunately going to continue the agony for another six or seven months," said opposition leader Mohamed ElBaradei.

"He's going to continue to polarize the country," said the Nobel Peace Prize winner. "He's continuing to get people even more angry and could result to violence. Whoever gives him that advice gave him absolutely the wrong advice. He just has to let go."

Mubarak's announcement largely rang flat in Tahrir Square, where thousands of protesters erupted in chants of "Down with Mubarak!" and "The people want the president to be judged!" following his announcement. Some waved shoes in the air -- a deep insult in the Arab world -- and said they would continue their demonstrations until Mubarak quits outright.

But Arab League Secretary-General Amre Moussa, a former Egyptian foreign minister, said demonstrators should weigh what Mubarak has said before responding.

"I'm aware that there are certain currents in Egypt that will not see that as satisfactory and they need more," Moussa, a possible presidential contender himself, told CNN. But, he added, "I believe that there is something new that has been offered."

Walid Tawfeeq, a Mubarak supporter, said not all Egyptians agree that Mubarak should step down immediately.

"Not everybody wants President Hosni Mubarak out," Tawfeeq said. "There are elements in the government that needed to be changed. ... There is reform. There is economic reform, but ... change will not happen overnight. There's not a magical button for change. Change will take time."

Mubarak has led Egypt for nearly 30 years since the 1981 assassination of his predecessor, Anwar Sadat, aided by an emergency decree that has allowed him to rule with an iron fist. But following demonstrations that have only grown in the past week, the 82-year-old former air force general told his people Tuesday night, "I have spent enough time serving Egypt."

"I will pursue the transfer of power in a way that will fulfill the people's demands, and that this new government will fulfill the people's demands and their hopes for political, economic and social progress," he said.

The Egyptian parliament has been suspended until a full judicial review is conducted of the November-December 2010 parliamentary elections.

In addition, a government-imposed curfew was shortened by a few hours compared to recent days, though many protesters have ignored the curfew. The new curfew lasts from 5 p.m. Wednesday until 7 a.m. Thursday.

Banks and schools have been closed during the demonstrations, teller machine screens were dark and gas stations have run out of fuel. Long lines snaked around bakeries and supermarkets as shops began to ration how much food customers could buy.

In Alexandria, protesters clashed with supporters of Mubarak, leaving 12 people injured, said Qutb Hassanein, a member of an opposition group. The military was called in to restore calm.

Mohammed Mahmoud, a protester, said he was hit in the head by a stick during the clash.

"We don't want him (Mubarak). We are staying here until we die," he said.

Mubarak's announcement came less than three weeks after a wave of protests forced Tunisia's longtime strongman to flee to Saudi Arabia in mid-January.

Protesters last week taunted, "Mubarak, Saudi Arabia is waiting for you." But despite calls for him to leave the country, the aging leader vowed Tuesday that "This dear country is my country ... and I will die on its land."

Opposition leader Ayman Nour called the speech "very depressing." Nour said Mubarak was already expected to step down at the end of his term -- but some believe Mubarak is maneuvering to have his son, Gamal, succeed him.

Mohammed Habib, deputy chairman of the officially banned Muslim Brotherhood, said Mubarak's speech was built around emotional appeals to his decades of military service and the presidency.

"After 30 years during which corruption and diminishing the strategic role of Egypt in the region became the norm, I do not feel it is time to appeal for people's emotion," Habib said. "We should say 'thank you' to him, 'and get out.' "

In Washington, President Barack Obama said he spoke with Mubarak soon after he announced he would not seek re-election.

Obama called for an orderly transition in Egypt that, he said, should be meaningful, peaceful and must begin now. The U.S. president stressed the Egyptian people will be the ones to determine their own leaders and destiny.

In Cairo, the U.S. ambassador to Egypt, Margaret Scobey, met Tuesday with ElBaradei and will be speaking with leaders of other political movements, a senior State Department official said. The official cautioned that Scobey's talks with ElBaradei doesn't mean the United States favors him.

As in Tunisia, the protests have been fueled by economic woes, including a dramatic rise in the cost of living coupled with high unemployment. Despite the government's food subsidies, people are struggling, with an estimated 40% of the country living in poverty.

The majority of Egypt's population -- and the vast majority of its unemployed -- is under 30, and many protesters are young men looking for economic opportunities and a better life.

As the demonstrations grew, Mubarak fired his Cabinet and ordered newly appointed Vice President Omar Suleiman to hold talks on political reform with opposition leaders.

Juan Cole, a Middle East historian at the University of Michigan, said he had expected the regime to endure the crisis with the support of the military, but that the military appears to have "cut Mubarak loose."

The demonstrations had turned ugly last Friday, when thousands of riot and plainclothes police used brutal force to crack down on people on the streets.

Unconfirmed reports suggest up to 300 people may have been killed during the protests, U.N. High Commissioner for Human Rights Navi Pillay said Tuesday. Human Rights Watch has reported 80 deaths from two hospitals in Cairo, 36 in Alexandria and 13 in Suez.

CNN has not been able to independently confirm the death toll. But since the weekend, the army has replaced police as the enforcers of security, and the gatherings, until Wednesday, had been largely peaceful.

In recent days, protests inspired by the Tunisian outcome have spread to Algeria, Yemen, Jordan and Sudan. Calls for political reform prompted Jordan's King Abdullah II Tuesday to dismiss his government and appoint a new prime minister. A Facebook page urged similar demonstrations in Syria.

And in Yemen, President Ali Abdullah Saleh -- who has been in office for 32 years -- said Wednesday he will not run for president nor hand over power to his son once his current term ends in 2013. Still, many Yemenis said they will proceed with their planned a "day of rage" protests Thursday.

John Entelis, director of Middle East studies at New York's Fordham University, said the Arab world is facing a "wave" of unrest sparked by the Tunisian revolt.

"If it were not for Tunisia, none of this would be happening at this time or in this way," Entelis said.